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pgmkernel - generate a convolution kernel
pgmkernel [ -weight
w ] width [ height ]
Generates a portable graymap array of
size width x height (or width x width if height is not specified)
to be used as a convolution file by pnmconvol. The data in the convolution
array K are computed according to the formula:
K(i,j) = 1 / ( 1 + w * sqrt((i-width/2)^2
+ (j-height/2)^2))
where w is a coefficient specified via the -weight
flag, and width and height are the X and Y filter sizes.
The output PGM
file is always written out in ASCII format.
The optional -weight
flag should be a real number greater than -1. The default value is 6.0.
The
computation time is proportional to width * height. This increases rapidly
with the increase of the kernel size. A better approach could be using
a FFT in these cases.
pnmconvol(1)
, pnmsmooth(1)
Alberto Accomazzi
(alberto@cfa.harvard.edu).
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